A significant portion of allergic conjunctivitis patients (approximately 30% of all ocular allergy sufferers) experience a more severe, late-phase allergic manifestation. This subpopulation of patients is not sufficiently treated with antihistamine therapy alone, and frequently develops a persistent chronic ocular surface inflammation due to repeated allergic events. The Conjunctival Allergen Challenge (CAC) is a proven model that effectively induces signs and symptoms of the acute allergic response. We have previously described variations of the CAC that can induce severe allergic responses suitable for evaluation of candidate anti-inflammatory compounds. Based on these efforts we have now developed a modified CAC model in which the timing and presentation of allergen has been designed simulate environmental allergen exposure. This model reproducibly creates signs and symptoms comparable to a late phase allergic response. The goal of the study described here was to validate this new model with a topical anti-inflammatory drug as a test treatment.

Methods

This Phase IV, IRB-approved, single-center, two-arm, placebo-controlled trial enrolled 9 volunteers 18 years of age or older with a history of allergic conjunctivitis. Subjects were challenged over a 3 day period using a unique conjunctival allergen challenge regimen designed to prolong the duration of allergic conjunctivitis signs and symptoms and create allergic inflammation. Qualified subjects were randomized to bilaterally receive either QID dosing with Prednisolone Phosphate 1.0% solution or vehicle for 7 days before repeating the challenge regimen. Itching, redness and chemosis were assessed at post treatment challenge sessions.

Results

Clinically and statistically significant differences between treatment arms were demonstrated for both itching and for redness.

Conclusions

The modified CAC was able to generate a chronic allergic inflammatory condition that was responsive to steroid therapy. This model should be useful for evaluating potential therapies for the treatment of chronic ocular allergy.